Monitoring device and method

ABSTRACT

The present invention relates to a method and an apparatus for providing information relating to disturbances and/or disease pattern based on a patient&#39;s breathing parameters. Preferably, the apparatus has multiple functionalities and provides information relating to different disturbances and/or disease patterns. In particular, the present invention relates to an apparatus for identifying different indications of a patient, the apparatus comprising a sensor, for sensing signals indicative of a patient&#39;s breathing, a processing unit, for processing and/or analyzing the signals, and display means for displaying the outcome of the processing and/or analysis. The corresponding method for identifying different indications of a patient comprises the steps of sensing signals indicative of a patient&#39;s breathing, processing and/or analyzing the signals, and displaying the outcome of the processing and/or analysis.

The present invention relates to a method and an apparatus for providinginformation relating to disturbances and/or disease pattern based on apatient's breathing parameters. Preferably, the apparatus has multiplefunctionalities and provides information relating to differentdisturbances and/or disease patterns.

Devices and methods for providing information relating to disturbancesand/or disease pattern based on a patient's breathing parameters areknown in the art. However, such devices and methods are complex andcomplicated to use and often require the provision and use of severalapparatuses or units in order to survey patient information, to analyzesuch information, and to provide the result of such analysis. Moreover,generally there is the need of a physician to supervise the surveying ofpatient information and/or to perform or control the analysis of thesurveyed data with the devices or methods known in the art.

Moreover, known devices often suffer from low calculating power andinaccurate method steps or algorithms leading to the provision ofimprecise or deficient information. Furthermore, the known methods anddevices do not distinguish between different disturbances and/or diseasepatterns such as hypopnea, apnea, periodics and snoring but merely countoccurring apneas.

Thus, it is an object underlying the present invention to provide amethod and apparatus which overcome the deficiencies of the prior art.In particular, it is an object of the present invention to provide amethod and/or device which allows an easy to use, reliable and cheapdetermination of a patient's, preferably different, disturbances and/ordisease patterns without the need of a physician to supervise the use ofthe device or method.

The object underlying the present invention is achieved with thesubject-matter defined in the independent claims. The dependent claimsrefer to preferred embodiments of the present invention.

In this application, the term patient will be used as referring to anypatient or potential patient, and particularly to any person using thedevice and/or method according to the present invention.

The present invention provides an apparatus for identifying differentindications of a patient, the apparatus comprising a sensor, for sensingsignals indicative of a patient's breathing, a processing unit, forprocessing and/or analyzing the signals, and display means fordisplaying the outcome of the processing and/or analysis. The apparatusis preferably adapted as a single or closed unit device providing itsfunctionality without the need of further devices or further processingof the derived information. Moreover, the device preferably is small insize so that it can be easily carried and used by a patient andpreferably fits in a patient's pocket. The apparatus according to thepresent invention is adapted to perform all steps and measures necessaryto provide information relating to one or more disturbances and/ordisease pattern based on a patient's breathing parameters. Preferably,the apparatus provides an indication, i.e., the reason or cause for amedical action, of the patient's disturbances and/or disease pattern,preferably of breathing disturbances and/or disease characteristics.

According to a preferred embodiment the apparatus according to thepresent invention, also referred to as screener, is adapted to identifymore than one, preferably two or more than two, and more preferablythree or more than three classes or types of possible patients,disturbances and/or disease pattern. This is preferably achieved bysurveying or screening signals indicative of a patient's breathing,processing and/or analyzing these signals and providing the outcome ofthe respective analysis as an easy distinguishable, preferably logical,e.g., YES or NO, signal. Preferably, the outcome of the respectiveanalysis represents an indication of the risk to suffer from one or moredisturbances and/or disease pattern.

Preferably, the apparatus is adapted to identify people who snore,people who suffer from sleep disordered breathing (OSA syndrome), and/orpeople who suffer from periodic disordered breathing.

People who snore, e.g., may suffer from a disturbed sleep generally atleast disturb their bed partner. This need not be a medical indicationfor, e.g., the need for using a CPAP device or therapy, but it is atleast a useful indication for the need for snoring devices. Thedetection of sleep disordered breathing (OSA syndrome) is considered amedical indication for, e.g., a CPAP device or therapy. The detection ofperiodic disordered breathing may be an indicator for a cardiologicalproblem.

Depending on the outcome of the analysis or the indication provided bythe apparatus, specific measures or therapies can or shall be consideredby a patient. For example, the advice may be given to a patient toconsult a physician, to get help by using a snoring device, to go to asleep lab, and/or to see a cardiologist.

According to a preferred embodiment, the apparatus surveys or screens asignal indicative of a patient's breathing, e.g. the nasal pressuresignal or the breathing flow signal, processes and/or analyses thederived signal, and provides an indication regarding the risk for one ormore disturbances and/or disease pattern, preferably snoring, disorderedbreathing (OSA), periodic disordered breathing, and/or otherdisturbances and/or disease pattern detectable on a patient's breathing.

A respective apparatus is preferably adapted as a multiple use device ora single use device. If the device is a multi use device the display canpreferably be reset, e.g., by an admitted person such as a physician. Ifthe device is designed as a single use or one way device it may bethrown away or preferably recycled after use. Preferably, the apparatusdoes neither store nor manage raw data nor is there the requirement toupload data to a further processing device, such as a PC.

The apparatus according to the present invention is preferablycomparatively small in size and, for example, has about the size of acigarette or cigarillo package. Preferably the apparatus has a handheldand/or pocket size. More preferably, the apparatus is a closed unitand/or single unit device. Such devices, e.g., provide a functional unitwithout depending on the connection to additional hardware or softwarein order to be operative and/or to fulfill the desired purpose.

The apparatus according to the present invention is particularlyadvantageous in that it is adapted to provide an indication for a numberof different medical indications, at low costs, requiring nocalibration, and/or allowing easy handling wherein no further analysisof the received data by a personal computer or the like is required. Afurther advantage of the present apparatus is that the above featuresand advantages of the present apparatus are achieved in a single orclosed, preferably hand-held, unit. This functional unit preferably hasa handheld and/or pocket size and provides easy determinable andreliable information as an output and is easy to handle by a patient,i.e., a medically untrained person.

In the following, the apparatus and method according to the presentinvention will be further described by way of example and by referenceto the figures of which

FIG. 1 shows an exemplary embodiment of a device according to thepresent invention which is suitable for providing information regardingthree different disturbances;

FIG. 2 shows a schematic structure and concept of a preferred device andmethod according to the present invention;

FIG. 3 shows a preferred schematic structure and concept of a device andmethod according to the present invention;

FIG. 4 shows preferred schematic concept or structure of a non-volatiledisplay or indicator according to the present invention;

FIG. 5 shows a preferred schematic structure and concept of a device andmethod according to the present invention;

FIG. 6 shows the schematic structure of a preferred processing andanalyzing algorithm according to the present invention;

FIG. 7 shows a preferred schematic flow diagram of a preferred schematicstructure and concept according to the present invention;

FIG. 8 shows a schematic basic structure and concept according to apreferred embodiment of the present invention; and

FIG. 9 shows the detection of periodic events according to a preferredembodiment of the present invention.

FIGS. 1 and 2 show an apparatus 1 for identifying different indicationsof a patient according to a preferred embodiment of the presentinvention. The apparatus is of a hand-held or pocket size so that it caneasily be carried and used by a patient. A preferred size of theapparatus is apparent from the also depicted general size of a humanhand 2. The apparatus 1 comprises a sensor (not shown) for sensingsignals indicative of a patient's breathing. Such sensor is preferably apressure sensor, a differential pressure sensor, and or a flow sensorfor sensing flow parameters of a patient's breathing. Preferably, apatient's breathing is guided by a suitable and generally knownstructure from a patient's mouth or preferably nose via a hose structureto the apparatus and the sensor, respectively. Preferably, the apparatuscomprises a nasal cannula 3, as e.g. shown in FIG. 2. The apparatusfurther comprises a processing unit, for processing and/or analyzing thebreathing signals derived from the patient's breathing and provided bythe sensor. The result or outcome of this processing and/or analysis isdisplayed by an indicator or display means 4. The result of the analysisis preferably displayed as an easy distinguishable signal, preferably alogical YES or NO signal. As shown in FIG. 1, the result is preferablyindicated by the activation of a light emitting device 5, such as anLED, which is either on or off. The visualization of the result may alsobe performed by using different colors of the display, e.g., green for apositive result and red for a negative result. Preferably, the apparatusanalyses the nasal pressure signal and gives an indication of the riskfor certain disturbances such as OSA and related problems.

The device according to FIG. 1 or 2 allows the detection of threedifferent disturbances and/or disease patterns. Preferably, the screeneris adapted to identify three classes of patients, namely people whosnore, people who suffer from sleep disordered breathing (obstructivesleep apnea or OSA-syndrome), and people who suffer from periodicdisordered breathing (Cheyne Stokes breathing or periodic CS). Thelatter may be an indicator for a cardiological problem. According topreferred embodiments, other or further disturbances may be detected bythe device according to the present invention.

As shown, the apparatus 1 is preferably a closed or single unit. Theapparatus is furthermore preferably of a small size and can be easilyused by a patient at home or in a private environment. Preferably, theapparatus comprises different means which are adapted to perform certainmeasures, as discussed in this application, so that no further means ormethod steps are required to perform the discussed analysis of apatient's breathing and to provide the result as an easy distinguishableinformation. The apparatus preferably comprises an energy source such asan accumulator or a rechargeable battery.

According to a preferred embodiment, as shown, e.g., in FIG. 3, theapparatus comprises means for performing algorithms or the like in orderto process and analyze the input signal sensed by the sensing unit.Preferably, the apparatus comprises a controller 6, preferably a PICcontroller, and a pressure sensor 7, preferably a low cost pressuresensor.

Preferably, particularly to avoid sensor calibration at production timethe sensor 7 is AC coupled to an A/D converter. Preferably, the sensoris connected to the processor 6 via an AC coupling 8. Preferably, thesensor 7 provides information to the controller 6 via a first channel 9and a second channel 10.

The nasal pressure signal, as sensed by the pressure sensor 7, ispreferably provided to the controller 6 via a first channel 9, e.g., aflow channel. Preferably, the nasal pressure signal is connected to anA/D1 input of the controller 6.

Preferably, there is provided a second channel 10, such a snore channel,for providing information regarding the sensed pressure signal to thecontroller 6. Preferably, particularly to avoid high sampling rates butstill allow the reliable detection of snoring, an envelope of theoriginal pressure signal is formed by an analog circuit. The envelopsignal is preferably connected to an A/D2 input of the controller 6.

In other words, according to a preferred embodiment, the sensed pressuresignal is firstly directly provided to the controller 6 via a firstchannel 9, also referred to as flow channel. Secondly, the sensedpressure signal is additionally processed, i.a., by means of, e.g., afilter 11 such as an HP Filter and/or an envelope means 12 for creatingan envelope signal or an envelope curve, and provided to the controller6 via a second channel 10, also referred to a snore channel, as anenvelope signal.

Preferably the controller 6 implements or is adapted to performalgorithms for different, according to an preferred embodiment three,indicators. The result of the indication performed is preferablyvisualized by means of at least one, preferably three and more,preferably a number corresponding to the number of possible indication,indicators or display elements 4. The display means 4 are preferablysimple LEDs 5 or non-volatile display elements 13, such as insingle-use-devices, to document the result of the study. As shown inFIG. 3, the controller 6 provides information to three differentindicators 4, namely a SNORE indicator, an OSA indicator, and aperiodic/CS indicator.

According to a preferred embodiment, the result of the indicationperformed by the apparatus 1 is displayed by a reusable display, such asfor multiuse devices. Such multiuse display is, e.g., an LED 5 or thelike. Preferably, also in multiuse devices the result of indication isshown by a permanent signal which the patient using the device has toshow to a chemist or doctor. Preferably, the display of the indicationor result has to be cleared afterwards by an authorized user.

For single use devices, the result or indication can be shown by anon-volatile or permanent indicator 13. Such indication or display canthen be shown to the doctor before the device is thrown away, comparableto the result of well known pregnancy tests. Preferably, the indicatoris realized by a small window 14 in the housing 15 of the apparatus 1comprising an inlet of, e.g., thermal paper or a thermal sensitivelacquer 16. Such paper or lacquer is, according to a preferredembodiment, blackened by a heat source or the like 17, such as an SMDresistor. Thereby, a permanent mark can be achieved at the respectivedisplay fields indicating diagnoses for disturbances as referred toabove, e.g., such as “snoring”, “OSA”, or “periodic/CS”.

FIG. 4 shows a part of the housing 15 of the apparatus 1 according of apreferred embodiment of the present invention having a transparentwindow 14 under which there is placed a thermal indicator 16, e.g., apiece of thermal paper. Underneath or in the vicinity of this thermalindicator there is arranged a heat source 17, such as an SMD resistor.The activation of the SMD resistor by the controller 6 will result inthe production of heat which will result in a change of color of thethermal indicator thereby providing a certain indication.

Preferably, the controller 6 comprises a data acquisition module 18 thatis adapted to read out the input to the controller 6, preferably theinput channels A/D1 and A/D2 from the analog inputs. According to thepreferred embodiment as discussed above, when an envelope signal isprovided via the snore channel 10 by means of a filter 11 and or anenvelope means 12, a sampling rate of about 5 Hz to 20 Hz and preferablyabout 10 Hz is preferably sufficient.

The flow signal as referred to herewith is preferably a pressure or aflow signal and preferably a nasal pressure or flow signal. Such signalis further referred to as flow or flow signal but is also meant to coverpressure or pressure signals.

Preferably, the flow and snoring signal as provided to the controller 6via the flow channel 9 and the snore channel 10, respectively, will beprovided to different processing modules of the processor to, e.g.,perform a different processing of or different algorithms on thesesignals. Preferably, the apparatus according to the present inventioncomprises at least one and more preferably at least three modules thatare adapted to perform at least one different analysis of the flowchannel signal and/or snoring channel signal. The algorithms preferablyused with the apparatus according to the present invention arepreferably simple enough to fit into a low cost processor but stillreliable and good enough to have sufficient sensitivity and specificityrequired for a screening device. These modules or algorithm modulespreferably calculate separate risk indicators. The raw data retrieved bythe data acquisition module 18 and underlying the calculation of riskindicators performed by the apparatus 1 preferably do not need to bestored. Preferably, the apparatus comprises two FIFOs forcharacteristics (basic and combined) to handle the data exchange betweenthe different modules.

FIG. 5 shows a preferred data acquisition module 18 having inputs A/D 1for the signal of flow channel 9 and A/D2 for the signal of the snorechannel 10. The data acquisition module 18 further comprises one or moremodules, preferably depending on the disturbances and/or disease patternto be indicated. Preferably, the data acquisition module 18 comprisesthe a snore detection module 19, an OSA detection module 20 and aperiodic/CS detection module 21, as shown in FIG. 5.

The snore detection module 19 preferably processes the signals providedvia the flow channel 9 and the signal provided via the snore channel 10in order to generate a snoring index 22. The OSA detection module 20preferably processes the signals provided via the flow channel 9 inorder to generate a risk indicator based on apnea and hypopnea, forexample a AHI 23. The periodic & CS detection 21 module preferablyprocesses the signals provided via the flow channel 9 in order togenerate a periodic index 24. Based on the snoring index 22, the AHI 23,and the periodic index 24 the processor 6 will control the indicator ordisplay 4.

The snore module 19, as shown in FIG. 6, preferably uses the inputsignal of cannel 10 providing the signal of the sensor 7 and the A/Dconverter 8. On this snore channel 10 the signal as output by the sensor7 and the converter 8 is preferably processed by a filter means 11 andan envelope means 12 creating an envelope signal. Filter means 11 ispreferably a high pass filter having a cut-off frequency of about 10 Hz.The upper cut-off frequency is preferably at approximately 50 to 100 Hz.

Via channel 10 there is thus preferably provided the envelope of theflow signal. Furthermore, the controller 6 and the snore module 19,respectively, preferably comprises a threshold detector means which isadapted to analyze the envelope signal provided via channel 10 and todetect the length of signal snoring events comprised in that signal.Preferably there is a minimum time length criterion for snoring eventsin order to prevent the snore module from detecting artefacts.

The snore module 19 furthermore preferably comprises a timer or counter26 for comparing the number of snoring events to a preset internal timebase or threshold and that calculates a snoring index 22.

Preferably, the apparatus 1 comprises an OSA module 20. The schematicstructure of a preferred OSA detection module 20 is shown in FIG. 7.Preferably, the module 20 is adapted to use envelope and threshold (timeand amplitude) algorithms to detect a reduction of the flow envelope.This is similar to a standard thermistor analysis. The differentiationbetween apnea and hypopnea can, according to the preferred embodiment,be discarded if just an AHI or respiratory disturbance index iscalculated to trigger the OSA indicator. However, the differentiationbetween apnea and hypopnea with separate thresholds is preferably used,particularly to increase spectivity within such algorithm.

The OSA detection module 20, as shown in FIG. 7, preferably receives thesignal provided via flow channel 9 as an input. The OSA detection modulepreferably comprises a detection means 27 for detection the envelope,the maximum and/or the minimum of the input signal. Based on the outputof the detection means 27 at least one calculation means 28 calculatesthe start and/or stop of an apnea, hypopnea and/or hyperventilation.Preferably, there are provided two calculation means 28, one forcalculating the start/stop of hypopnea and hyperventilation and one forcalculating the start/stop of apnea and hyperventilation. Thecalculation means 28 provides a moving hypopnea index HI and/or a movingapnea index AI as an output. Based on the moving hypopnea index HI, themoving apnea index AI and information provided by a counter means 30 aAHI calculation means 29 calculates an apnea/hypopnea index 23. Thecounter means 30 calculates sample counters as a timebase on the basisof the signal provided via flow channel 9.

Preferably, the OSA module provides additional information such as thelength of apneas, hypopneas and/or hyperventilations. According to apreferred embodiment, such information is used in the periodic/CS module21 as further described below.

The periodic and CS detection module 21, e.g. as shown in FIG. 8, fordetecting periodic and Cheyne Stokes patterns preferably performs itsprocessing on the basis of hypopnea pause and length information (whichincludes apnea as a special case). Preferably, the periodic and CScalculation means 21 comprises an envelope/minimum/ calculation means(not shown) as referred to with regard to FIG. 7 and/or and indexcalculation means 31 for calculating a moving index for periodicity,e.g., for autocorrelation index by epochs. Preferably, the indexcalculation means receives information regarding the average hypopnealength, the average hypopnea pause and/or the hyperventilation length asinput parameters as well as the timebase information as referred toabove with regard to counter means 30. The respective informationrelating to hypopnea automatically include apnea information as aspecial case. Preferably, the periodic and CS detection module 21 andthe index calculation means 31 provides the periodic index 24 comprisingan periodicity index and/or a Cheyne Stokes index as an output.

Such periodic or CS module 21 preferably detects central periodicbreathing patterns from the nasal cannula signal as provided, e.g., viaflow channel 9. Preferably, the module for detection of CS 21 uses thefact that the shape of the envelop of flow maxima is periodic.Preferably, the periodic or CS module 21 abstracts the flow curve infalling gradients (FG) and rising gradients (RG) as well as apneas orhypopneas with a horizontal shape. An indicator for periodic apneas canbe calculated from the frequency of occurrences of the RG-FG complex andshort epochs. If higher spectivity is needed, the maxima of the RG-FGcomplexes can be auto-correlated to get a number for the regularity.

The detection of periodic events is shown in e.g. FIG. 9 identifyingrising gradients RG, which are particularly informative with regard tohyperventilation, falling gradients FG, with are particularlyinformative with regard to flow limitation of central breathingdisorders, and apneas (central) with a horizontal shape on the basis ofan exemplary flow curve (flow over time).

It is expected that a normal or just “OSA” disordered breathing patternwill not have an adequate number of RG-FG complexes to indicate“periodic”. Thus, periodicity is not determined via FFT or the like.

Preferably, the apparatus comprises a pressure and/or flow sensor,analog electronics, a PIC controller and a three color LED

The apparatus according to the present invention is preferably adaptedas a single unit or closed unit device for single or multi uses. Theapparatus is easy to use and provides a reliable and easy to determineinformation as a output. This allows the apparatus to be used at home bya patient. Once a patient has used the device, the results orindications of such use can be shown to a doctor or physician. There isno need to provide specific means or adaptors to read out the indicationachieved by the apparatus according to the present invention. Rather,the information can be read out easily and reliably even by an unskilledperson.

The apparatus according to the present invention is particularlyadvantageous in that it provides indicators for different medicalindications, has low material costs, requires no calibration, is easy tohandle, and/or does not require further processing of the sensed date bya PC or the like.

1. Apparatus 1 for identifying different indications of a patient, theapparatus comprising a sensor 7, for sensing signals indicative of apatient's breathing, a processing unit 6, for processing and/oranalyzing the signals, and display means 4 for displaying the outcome ofthe processing and/or analysis.
 2. Apparatus according to claim 1,wherein the result of the processing and/or analyzing is displayed as aneasy distinguishable signal, preferably a logical YES or NO signal. 3.Apparatus according to claim 1, wherein the apparatus 1 is a closedunit.
 4. Apparatus according to claim 1, wherein the apparatus 1 is ahandheld and/or pocket size device.
 5. Apparatus according to claim 1,wherein the apparatus 1 comprises an energy source such as anaccumulator or a rechargeable battery.
 6. Apparatus according to claim1, wherein the apparatus 1 comprises a flow channel 9 and/or a snorechannel
 10. 7. Apparatus according to claim 1, wherein the apparatus 1further comprises an A/D converter
 8. 8. Apparatus according to claim 1,wherein the apparatus 1 comprises a filter means 11 and an envelopemeans 12 provided in the snore channel means
 10. 9. Apparatus accordingto claim 1, wherein the apparatus 1 comprises a snore detection module19, an OSA detection module (20) and a periodic and/or CS detectionmodule (21) for providing a snoring index 22, an apnoe/hypopnoe index 22and/or a periodic index
 24. 10. Method for identifying differentindications of a patient, preferably by use of an apparatus according toclaim 1, comprising the steps of sensing signals indicative of apatient's breathing, processing and/or analyzing the signals, anddisplaying the outcome of the processing and/or analysis.